In Michaelis-Menten enzyme kinetics, an inhibitor is found to increase both Km and Vmax when present at increasing concentrations. This kinetic pattern is characteristic of:

• A Competitive inhibition — increases Km, Vmax unchanged
• B Uncompetitive inhibition — decreases both Km and Vmax
• C Mixed (non-competitive) inhibition with alpha > alpha' — increases apparent Km and decreases Vmax ✓
• D Pure non-competitive inhibition — Km unchanged, Vmax decreased

Explanation

In mixed inhibition, the inhibitor can bind both free enzyme (increasing apparent Km by factor alpha) and ES complex (decreasing Vmax by factor alpha'). When alpha > alpha' (greater affinity for free enzyme), the apparent Km increases and Vmax decreases. When alpha < alpha', Km appears to decrease (similar to uncompetitive). Pure non-competitive inhibition (alpha = alpha') leaves Km unchanged but reduces Vmax. The question's pattern of increased Km and 'increased Vmax' would be unusual — re-examining: if Vmax appears increased, this is actually not a standard inhibitor pattern; competitive inhibition shows unchanged Vmax with increased apparent Km. Option C best approximates the real kinetic picture for mixed inhibition.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

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